Method and system for processing handover in heterogeneous mobility protocol mixed networks and mip client device

ABSTRACT

Provided are a method for processing handover to provide IP mobility for mobile user equipment, a system thereof, and a Mobile IP (MIP) client device. The method processing handover at a home agent in a heterogeneous protocol mixed network includes: at a home agent, creating a Proxy Mobile IP (PMIP) tunnel when user equipment accesses a PMIP network; at the home agent, creating a Client Mobile IP (CMIP) tunnel when a CMIP network is accessed due to handover of the user equipment; and at the home agent, severing the PMIP tunnel when the user equipment completes performing handover.

TECHNICAL FIELD

Exemplary embodiments of the present invention relate to a method forprocessing handover to provide IP mobility for mobile user equipment, asystem thereof, and a Mobile IP (MIP) client device; and, moreparticularly, to a method for processing handover in a heterogeneousmobility protocol mixed networkS, a system thereof, and a MIP clientdevice, which are for providing mobility of mobile user equipment in aheterogeneous mobility protocol mixed networkS where a method forproviding mobility for mobile user equipment is changed to a ClientMobile IP (CMIP) scheme or a Proxy Mobile IP (PMIP) scheme according tothe network to be accessed.

In an embodiment of the present invention, a client mobile Internetprotocol (CMIP) and a proxy mobile Internet protocol (PMIP) will bedescribed as an example of a heterogeneous mobility protocol. However,the present invention is not limited thereto. A method for processinghandover between two different mobility protocols such as CMIP and PMIPis referred as a hybrid mobile Internet protocol (IP).

In an embodiment of the present invention, a CMIP IP version 4 or a PMIPIP version 4 is described. However, the present invention is not limitedthereto. The present invention may be applied to an IP version 6 of CHIPand PMIP.

In case of CMIP, mobile user equipment and a home agent (HA) operate ina Collocated Care-of-Address (CCoA) mode where client-server based IPmobility is provided by allocating a CCoA to mobile user equipmentwithout including an additional function for providing IP mobility at anaccess router. Alternately, mobile user equipment and a home agent (HA)may operate in a Foreign Agent Care-of-Address (FA CoA) mode by loadingIP mobility at an existing access router. Accordingly, an embodiment ofthe present invention is described based on CMIP that operates in a CCoAmode without loading IP mobility at an access router. However, thepresent invention may be applied to CMIP that operates in a FA CoA mode.

An application scope of the present invention is not limited to aspecific wireless access network. The present invention may be appliedto at least two wireless access networks. Therefore, heterogeneouswireless access networks are described as a Worldwide Interoperabilityfor Microwave Access (WiMAX) network and a Universal MobileTelecommunications System (UMTS) network in an embodiment of the presentinvention. However, the present invention is not limited thereto. Thatis, throughout the specification, an embodiment of the present inventionis described based on a WiMAX network applied with CMIPv4 operating in aCCoA mode and a UMTS network applied with PMIPv4. However, the presentinvention is not limited thereto. Hereinafter, an access network withCMIP applied to is referred as a CMIP network, and an access networkwith PMIP applied to is referred as a PMIP network.

A simultaneous binding mode is applied in an embodiment of the presentinvention. In the simultaneous binding mode, a home agent maintains aCMIP tunnel created with mobile user equipment through a CMIP networkand a PMIP tunnel created with an access gateway of a PMIP network whenmobile user equipment moves between a CMIP network and a PMIP network.However, the present invention is not limited thereto. The presentinvention may be applicable without the simultaneous binding mode. Thatis, the present invention may be applicable when a new PMIP tunnel (or anew CMIP tunnel) is created after canceling an existing CMIP tunnel (oran existing PMIP tunnel) during handover.

In an embodiment of the present invention, a handover process isperformed based on handover policy and network configuration informationdownloaded from a Media Independent Information server (MIIS) whenmobile user equipment moves between a WiMAX network and a UMTS network.The MIIS is defined in IEEE 802.21 access network Media IndependentHandover (MIH). For this, it is assumed that an access gateway of a UMTSnetwork includes a MIH function. However, the present invention is notlimited to IEEE 802.21 access network MIH.

In an embodiment of the present invention, a handover process isperformed between networks each supporting a different mobilityprotocol. For example, a handover process is performed for moving from aPMIP network (UMTS network) to a CMIP network (WiMAX network) or formoving from a CMIP network (WiMAX network) to a PMIP network (UMTSnetwork). Meanwhile, a horizontal handover process or a verticalhandover process is performed between networks supporting the sameprotocol according to a typical method. Accordingly, the detaileddescriptions thereof are omitted because it is not necessary to describethe present invention.

BACKGROUND ART

Lately, various types of portable communication devices such as anotebook computer supporting wireless network, a personal digitalassistant (PDA), and a portable telephone having a data transmissionfunction have been popular. Hereinafter, such a portable communicationdevice is referred as user equipment (UE) through the specification.Further, the necessity of IP mobility of user equipment have beenincreased as wireless Internet services have been activated based ondifferent types of technologies such as a wireless local area network(WLAN), a 3G cellular system, and IEEE 802.16. The providing IP mobilityof user equipment means that a seamless service is guaranteed when an IPaddress is changed because user equipment changes a subnet.

Due to the necessity of IP mobility, various methods have beenintroduced to provide IP mobility to mobile user equipment. As one ofrepresentative technologies for providing IP mobility, InternetEngineering Task Force (IETF) has introduced a Client Mobile InternetProtocol (CMIP) and a Proxy Mobile IP (PMIP). Here, the PMIP has been inprogress for standardization. Particularly, an IP version 6 of PMIP hasbeen completely standardized, and an IP version 4 of PMIP has been inprogress for standardization.

In the CMIP, mobile user equipment informs a home agent of a currentlocation (IP mobility). For this, the CMIP requires mobile userequipment to have a MIP client function. The mobile user equipmentregisters at the home agent using a MIP signaling message when themobile equipment moves to other access point.

One of advantages of the CMIP is to provide client-server based IPmobility between mobile user equipment and a home agent by allocating aCollocated Care-of-Address (CCoA) to mobile user equipment without anadditional function loaded at an existing access router for providing IPmobility.

However, the CMIP is ineffective in view of utilization of wirelessresources and power consumption of user equipment because a locationregistration signal must be transmitted and received through a wirelessperiod. Further, it is required to allocate a new IP address wheneveruser equipment changes a subnet. Accordingly, handover isdisadvantageously delayed due to the allocation of new IP address.Moreover, user equipment must have a MIP function for the CMIP.

In order to compensate such disadvantages of CMIP, the IETF has beenstandardizing a PMIP. The PMIP is a protocol providing network based IPmobility. The PMIP provides IP mobility even to mobile user equipmentnot having a MIP function.

In the PMIP, an IP mobility providing function of an access routerperforms a location registration procedure instead of mobile equipment.Accordingly, the PMIP is effective in view of wireless resourceutilization and power consumption because it is not required to transmitor to receive a location registration signal in a wireless section.Although the mobile user equipment changes a subnet, the mobile userequipment uses the same IP address. That is, it is not required toallocate a new IP address. Accordingly, handover delay may be reduced.Due to such advantages of the PMIP, the PMIP is included in a WiMAXForum network Architecture Release Version 1.2.0.

However, the CMIP and the PMIP have been designed to operateindependently to provide IP mobility to user equipment. Due to such areason, it has been required to embody a mobility protocol of aheterogeneous network as only one of the CMIP and the PMIP to provide aseamless service while mobile user equipment performs a handoverprocess.

For example, mobile user equipment can receive a seamless service withina network supporting a CMIP if mobility is provided based on a CMIP. Or,mobile user equipment can receive a seamless service within a networksupporting a PMIP if mobility is provided based on a PMIP. However, theuser equipment provided mobility based on a CHIP cannot have a seamlessservice if the user equipment enters to a network supporting a PMIP. Or,the user equipment provided mobility based on a PMIP cannot have aseamless service if the user equipment enters to a network supporting aCMIP.

Furthermore, the PMIP networks coexist with the CHIP networks becausethe PMIP and the CMIP were introduced at different times. Therefore, ithas been required to develop a method for providing mobility of mobileuser equipment to provide a seamless service although user equipmentmoves between the CMIP network and the PMIP network.

In order to realize all networks as a PMIP network, it is required toload an IP mobility providing function at an access router. Accordingly,an access router has to be replaced or modified in case of existing CHIPnetworks.

DISCLOSURE [Technical Problem] [Technical Solution]

Accordingly, it is an object of the present invention to overcome theprior art problems.

An embodiment of the present invention is directed to a method forprocessing handover to provide mobility of user equipment in aheterogeneous mobility protocol mixed network, a system thereof, and amobility Internet protocol (MIP) client device.

Another embodiment of the present invention is directed to a method forprocessing handover to provide IP mobility through handover between aCMIP network and a PMIP network, a system thereof, and a MIP clientdevice.

Still another embodiment of the present invention is directed to amethod for processing handover to provide mobility of mobile userequipment in a heterogeneous mobility protocol mixed network where amobility providing scheme is changed to a CMIP or a PMIP according to anaccess network, a system thereof, and a MIP client device.

Yet another embodiment of the present invention is directed to a methodfor process handover to provide IP mobility to user equipment in aheterogeneous mobility protocol mixed network by applying a CMIP to awireless access network having difficulty to modify an access router andby applying a PMIP to a wireless access network capable of modifying anaccess router, a system thereof, and a MIP client device.

Other objects and advantages of the present invention can be understoodby the following description, and become apparent with reference to theembodiments of the present invention. Also, it is obvious to thoseskilled in the art to which the present invention pertains that theobjects and advantages of the present invention can be realized by themeans as claimed and combinations thereof.

In accordance with an embodiment of the present invention, a method forprocessing handover in a heterogeneous mobility protocol mixed networkincludes creating a Proxy Mobile IP (PMIP) tunnel at a home agent whenuser equipment accesses a PMIP network; creating a Client Mobile IP(CMIP) tunnel at the home agent when a CMIP network is accessed due tohandover of the user equipment; and canceling the PMIP tunnel at thehome agent when the user equipment completes performing handover.

In accordance with another embodiment of the present invention, a methodfor processing handover in a heterogeneous mobility protocol mixednetwork includes: creating a CMIP tunnel at a home agent when userequipment accesses a CMIP network; creating a PMIP tunnel at the homeagent when the user equipment decides to perform handover; and cancelingthe CMIP tunnel at the home agent when the user equipment completesperforming handover by accessing the PMIP network.

In accordance with still another embodiment of the present invention, amethod for processing handover includes: being allocated with a home IPaddress to form a PMIP tunnel by accessing a PMIP network at userequipment; accessing a CMIP network when the user equipment decide toperform handover; forming a CMIP tunnel to a home agent at the userequipment; and canceling the PMIP tunnel by caning the PMIP network whenthe user equipment completes performing handover.

In accordance with yet another embodiment of the present invention, amethod for processing handover includes: forming a CMIP tunnel to a homeagent by accessing a CMIP network at user equipment; forming a PMIPtunnel by informing beginning of handover according to a decision toperform handover at the user equipment; completing performing handoverby accessing the PMIP network at the user equipment; and requesting thehome agent to cancel the CMIP tunnel.

In accordance with yet another embodiment of the present invention, aheterogeneous mobility protocol mixed system includes an access gatewayof a PMIP network configured to register an IP address of user equipmentat a home agent by loading a Proxy Mobility Agent (PMA) when the userequipment accesses a PMIP network; and the home agent configured toregister the IP address of the user equipment when the user equipmentaccesses the CMIP network, allocate a home IP address to the userequipment, create a CMIP tunnel to the user equipment, create a PMIPtunnel to an access gateway of the PMIP network according to the IPaddress registration of the user equipment through the access gateway ofthe PMIP network, allocate a home IP address to the user equipment, andcancel a MIP tunnel of a previous access network when the user equipmentcompletes performing the handover.

In accordance with yet another embodiment of the present invention, amobile IP client device includes a MIP sensor configured to sensewhether a network to be accessed is a CMIP network or a PMIP network; afirst MODEM configured to perform wireless access to a base station ofthe PMIP network; a second MODEM configured to perform wireless accessto a base station of the CMIP network; a MIP driver configured toprovide IP mobility of user equipment by performing a MIP clientfunction; and an access controller configure to drive one of the firstMODEM and the second MODEM according to the sensing result of the MIPsensor and control driving the MIP driver.

In accordance with yet another embodiment of the present invention, amethod for processing handover in a heterogeneous mobility protocolmixed network includes: allocating a home IP address to user equipmentwhen the user equipment accesses a PMIP network, performing a bindingprocess for the user equipment and transmitting and receiving data bygenerating a PMIP tunnel; starting handover to a CMIP network accordingto a decision to perform handover to the CMIP network; canceling thehandover to the CMIP network when a handover process is decided toperform to the PMIP network before completing performing the handover tothe CMIP network; and transmitting and receiving data through the CMIPnetwork.

In accordance with yet another embodiment of the present invention, amethod for processing handover in a heterogeneous mobility protocolmixed network includes: allocating a home IP address at user equipmentwhen the user equipment accesses a CMIP network, performing a bindingupdate process for the user equipment, and transmitting and receivingdata by generating a CMIP tunnel; starting performing a handover processto a PMIP network according to a decision to perform handover to thePMIP network; canceling the handover to the PMIP network according to are-decision to perform handover to the CMIP network before completingthe handover to the PMIP network; and transmitting and receiving datathrough the CMIP network.

In accordance with yet another embodiment of the present invention, amethod for processing handover in a heterogeneous mobility protocolmixed network includes: transmitting and receiving data by performing aCMIP registration procedure when user equipment accesses a CMIP network;maintaining a corresponding PMIP resource in an idle station byperforming a PMIP network accessing process and a PMIP registrationprocess during transmitting and receiving data; and performing ahandover process by activating the PMIP resource in the idle stateaccording to a decision to perform handover from a CMIP network to aPMIP network.

In accordance with yet another embodiment of the present invention, amethod for processing handover in a heterogeneous mobility protocolmixed network includes: transmitting and receiving data by performing aPMIP registration procedure when user equipment accesses a PMIP network;maintaining a corresponding CMIP resource in an idle state by performinga CMIP access process and a CMIP registration process while transmittingand receiving data; and performing handover by activating the CMPresource in the idle state according to a decision to perform handoverfrom a PMIP network to a CMIP network.

As described above, the present invention relates to a hybrid mobile IPmechanism for interworking a WiMAX network and a UMTS network. In ahybrid mobile IP system, IP mobility of mobile user equipment isprovided by a CMIP while the mobile user equipment is accessing oneaccess network. When the user equipment moves to the other accessnetwork, the IP mobility of the mobile user equipment is provided by aPMIP.

The hybrid mobile IP provides IP mobility handover between two accessnetworks, one having a CMIP loaded and the other having a PMIP loaded.

ADVANTAGEOUS EFFECTS

As described above, the embodiments of the present invention providemobility of mobile user equipment by performing handover in aheterogeneous mobility protocol mixed network.

That is, the embodiments of the present invention provide a seamlessservice to one mobile user equipment in a PMIP network and a CMIPnetwork. In other words, the embodiments of the present inventionprovide IP mobility to mobile user equipment in a heterogeneous mobilityprotocol mixed network through interworking of a CMIP and a PMIP byapplying a CMIP to a wireless access network having difficulty to modifyan access router or by applying a PMIP to a wireless access networkwhere an access router is easily modified.

Further, the embodiments of the present invention enable handoverbetween two networks when IP mobility is applied between a CMIP appliedWiMAX network and a PMIP applied UMTS network. Accordingly, handoverbetween heterogeneous wireless networks can be performed withoutinterruption of communication.

Moreover, the continuity of an application service can be provided byperforming handover between heterogeneous networks without interruptingcommunication.

DESCRIPTION OF DRAWINGS

FIG. 1 is a table illustrating standardization activities forinterworking of different wireless access networks.

FIG. 2 is a diagram illustrating an interworking network architectureintroduced in 3GPP and WiMAX forum.

FIG. 3 is a diagram illustrating a heterogeneous mobility protocol mixednetwork in accordance with an embodiment of the present invention.

FIG. 4 is a diagram illustrating a MIP client device in accordance withan embodiment of the present invention.

FIG. 5 is a diagram illustrating an initial access procedure foraccessing a UMTS network.

FIG. 6 is a flowchart illustrating a method for processing handover in aheterogeneous mobility protocol mixed networks in accordance with anembodiment of the present invention.

FIG. 7 is a diagram illustrating an initial access procedure foraccessing a WiMAX network.

FIG. 8 is a flowchart illustrating a method for processing handover in aheterogeneous mobility protocol mixed networks in accordance with asecond embodiment of the present invention.

FIG. 9 is a flowchart illustrating a method for processing handover in aheterogeneous mobility protocol mixed networks in accordance with athird embodiment of the present invention.

FIG. 10 is a flowchart illustrating a method for processing handover ina heterogeneous mobility protocol mixed networks in accordance with afourth embodiment of the present invention.

BEST MODE

Exemplary embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. The presentinvention may, however, be embodied in different forms and should not beconstructed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the present inventionto those skilled in the art. Throughout the disclosure, like referencenumerals refer to like parts throughout the various figures andembodiments of the present invention. The drawings are not necessarilyto scale and in some instances, proportions may have been exaggerated inorder to clearly illustrate features of the embodiments.

FIG. 1 is a table illustrating standardization activities forinterworking of wireless access networks.

Lately, various types of wireless access networks have been embodied allover the world. Accordingly, many researches and studies have been madefor interworking of Global Systems for Mobile communication (GSM),Wideband Code Division Multiple Access (WCDMA), Code Division MultipleAccess (CDMA), Worldwide Interoperability for Microwave Access (WiMAX),Wi-Fi, and 3rd Generation Partnership Project Long Term Evolution (3GPPLTE). Function architecture has been standardized to provideinterworking between such access networks.

The table of FIG. 1 shows standardization activities of 3GPP, WiMAXForum, Internet Engineering Task Force (IETF), and Institute ofElectrical and Electronics Engineers (IEEE). Like LTE, HSPA/WCDMA, andGSM, 3GPP has been standardizing network architecture for interworkingbetween 3GPP access networks. The network architecture supportsinterworking between a 3GPP based access network and non-3GPP accessnetworks such as WiMAX, Wi-Fi, and CDMA.

A Client Mobile IP (CMIP) and a Proxy Mobile IP (PMIP) have beenconsidered as a candidate for a mobility protocol for a 3GPP structurefor interworking with other access network. In the WiMAX Forum, a 3GPPinteraction structure has been modified as a baseline framework forinteraction.

FIG. 2 is a diagram illustrating an interworking network introduced in3GPP and WiMAX Forum. That is, FIG. 2 illustrates an interworkingstructure for interaction between WiMAX and 3GPP LTE defined in 3GPP TS23.402 and a WiMAX Forum baseline draft.

In such a structure, WiMAX access is considered as a non-3GPP networkhaving reliability, and an ASN_GW, an access gateway of WiMAX isdirectly connected at 3GPP PDN-GW. Further, an ASN-GW is directlyconnected to other network constituent element of PCRF, AAA(Authentication, Authorization, Accounting), 3GPP PS core network.

Meanwhile, a non-3GPP network such as a Wireless local area network(WLAN) is connected to a PDN_GW through an ePDG. Here, the ePDG performsauthentication, authorization, and accounting necessary for interworkingwith a network not having reliability instead of a 3GPP core network. Insuch a structure, the PDN-GW is an anchor point for interworking withother wireless access network.

When IP mobility function is configured for providing IP mobility, anoptimal location for a home agent (HA) function is a PDN-GW. A foreignagent (FA) function may include a GGSN, a S-GW, an ASN-GW, and an ePDG.

3GPP TS 23.402 introduces three IP mobility protocols for interworkingbetween 3GPP wireless access and non-3GPP wireless access. The three IPmobility protocols are as follows.

(1) CMIP version 4 operating in a FA CoA mode

(2) PMIP version 6

(3) MOBIKE (IKEv2 Mobility and Multihomming: RFC 4555) for mobilitymanagement in non-3GPP network having no reliability

An IP mobility solution, not considered in a 3GPP and WiMAX Forum, is aCMIP that operates in a CCoA mode. In the CCoA mode, the CMIP does notrequire an access gateway such as a GGSN, a S-GW, an ASN-GW, and an ePDGto have a FA function. The CMIP also allows mobile user equipment todirectly register with own IP address at a home agent without help of aFA.

An embodiment of the present invention relates to a hybrid mobile IP forinterworking between heterogeneous wireless access networks. When mobileuser equipment moves in a wireless network having an access gateway nothaving a FA function in case of a CMIP or not having a PMA/MAG functionin case of a PMIP, IP mobility may be provided by a CMIP operating in aCCoA mode. When mobile user equipment moves to a wireless network havingan access gateway having a FA function or a PMA/MAG function, the IPmobility of mobile user equipment may be provided by one of a CMIP and aPMIP in a FA CoA mode.

FIG. 3 is a diagram illustrating a heterogeneous mobility protocol mixednetwork in accordance with an embodiment of the present invention.

That is, FIG. 3 is a diagram for describing hybrid mobile IP operation.It illustrates hybrid mobile IP operation for handover between a WiMAXnetwork and a UMTS network.

A Gateway GPRS Support Node 30 (GGSN), an access router of a UMTSnetwork, includes a Proxy Mobile IPv4 (PMIP v4) Proxy Mobility Agent(PMA) function. An Access Service Network Gateway 20 (ASN-GW) of theWiMAX network does not include a Proxy Mobile IP (PMIP) function.

While user equipment 10 is accessing the WiMAX network, IP mobility isprovided to the user equipment 10 by a CMIP operating in a CCoA mode.The user equipment 10 registers an own IP address at a home agent (HA)40 using the CMIP protocol. A correspondent node (CN) 50 communicatingwith the user equipment 10 transmits and receives user traffic throughthe HA 40.

When the mobile user equipment 10 performs handover to the UMTS network,the GGSN 30 senses it and the PMA function of the GGSN 30 registers theIP address of the mobile user equipment 10 to the HA 40. While themobile user equipment 10 is accessing the UMTS network, the CMIPfunction of the mobile user equipment 10 does not operate. The mobileuser equipment 10 operates in simple IP mode.

When the mobile user equipment 10 performs handover from the UMT networkto the WiMAX network, the CMIP function of the mobile user equipment 10operates again. The user traffic is transmitted and received through aMIP tunnel between the mobile user equipment and the home agent (HA).

Such hybrid mobile IP (IMP) operation will be described in detailhereinafter.

As shown in FIG. 3, a heterogeneous mobility protocol mixed networkincludes a WiMAX network with CMIP-CcoA mode applied and a UMTS networkwith PMIP applied. The WiMAX and the UMTS network may be overlapped toeach other or independent from each other. Further, the WiMAX networkand the UMTS network may be partially overlapped to each other.

The ASN-GW 20 of the WiMAX network may not have any function forproviding IP mobility and may include a Foreign Agent (FA) function forallocation a CCoA to the mobile user equipment 10. Such an ASN-GW 20 ofthe WiMAX network has a function identical to that of an ASN-GW of atypical CMIP network.

The GGSN 30 of the UMTS network has a PMIP function. Such a GGSN 30creates an IP tunnel with the HA 40 and performs a location registrationof mobile user equipment 10 when handover is performed.

The HA 40 transfers data received from the mobile user equipment 10 tothe correspondent node (CN) 50 through an IP tunnel or transfers datareceived from the CN 50 to the mobile user equipment 10 through the IPtunnel.

The HA 40 has an access network detection function and a dual IP tunnelcreation function. That is, the access network detection functiondetermines whether the mobile user equipment 10 accesses a CMIP networkor a PMIP network in order to enable interworking between the CMIPnetwork and the PMIP network. Further, the dual IP tunnel creationfunction creates an IP tunnel to the mobile user equipment 10 or to theGGSN 30.

The access network detection function detects an access network of themobile user equipment 10 through a source address recorded in a headerof a message received in location registration of the mobile userequipment 10, that is, when binding update is requested. The sourceaddress may be an address of the user mobile equipment when the mobileuser equipment 10 accesses the CMIP network (i.e., WiMAX network in FIG.3). Further, the source address may be an address of the GGSN 30 whenthe mobile equipment 10 accesses the PMIP network (i.e., WiMAX networkin FIG. 3).

Further, the access network detection function uses a network identifierincluded in a MIP registration message received in location registrationof the mobile user equipment 10 (when binding update is requested) todetermine whether the mobile user equipment 10 access the CMIP networkor the PMIP network. Here, the network identifier may be a mobilityprotocol identifier, and the network identifier may be included anoption field of a MIP registration message. The network identifier maybe one of a code informing that the mobile user equipment 10 accessesthe CMIP network or a code informing that the mobile user equipment 10accesses the PMIP network.

The dual IP tunnel creation function may create an IP tunnel differentlyaccording to a network that the mobile user equipment 10 accesses. Thatis, the HA 40 performs the dual IP tunnel creation function to create anIP tunnel to the mobile user equipment 10 when the mobile user equipment10 accesses the CMIP network and to create an IP tunnel to the GGSN 30when the mobile user equipment 10 accesses the PMIP network.

Hereinafter, the IP tunnel from the HA 40 to the mobile user equipment10 is referred as a CMIP tunnel, and the IP tunnel from the HA 40 to theGGSN 30 is referred as a PMIP tunnel.

The mobile user equipment 10 in accordance with an embodiment of thepresent invention includes constituent elements to seamlessly access aPMIP network or a CMIP network and being provided with mobilityaccording to CMIP or PMIP. Such a MIP client device of the mobile userequipment 10 is shown in FIG. 4.

FIG. 4 is a diagram illustrating a MIP client device in accordance withan embodiment of the present invention.

As shown in FIG. 4, the MIP client device in accordance with anembodiment of the present invention includes a MIP sensor 11, an accesscontroller 12, a UMTS MODEM 13, a WiMAX MODEM 14, and a MIP operationunit 15.

The MIP sensor 11 senses a CMIP network or a PMIP network that themobile user equipment 10 currently tries to access (initial access orhandover access). The HIP sensor 11 receives a signal transmitted from abase station (or Node-B (NB)) of an access network through acorresponding MODEM and analyzes the received signal to determine one ofthe CMIP network and the PMIP network. Here, the signal may be anadvertisement message or a pilot signal. Alternately, the MIP sensor 11receives a network identifier transmitted from one of a CMIP network anda PMIP network through a corresponding MODEM and analyzes the receivednetwork identifier to sense one of the CMIP network and the PMIPnetwork. Further, the MIP sensor 11 determines one of the CMIP networkand the PMIP network according to a CMIP access instruction or a PMIPaccess instruction input from a user.

The access controller 12 controls at least one of the WiMAX MODEM 14 andthe UMTS MODEM 13 according to the sensing result of the MIP sensor 11.Further, the access controller 12 controls the MIP operation unit 15.The access controller 12 controls the WiMAX MODEM 14 and the MIPoperation unit 15 to interwork each other when the mobile user equipment10 accesses the CMIP network. Hereinafter, such interworking the MIPoperation unit 15 with the UMTS MODEM 13 or the WiMAX MODEM 14 isreferred as activation.

Meanwhile, the access controller 12 may activate all of the UMTS MODEM13, the WiMAX MODEM 14, and the MIP operation unit 15. In this case, theaccess controller 12 temporally activates one of the UMTS MODEM 13 andthe WiMAX MODEM 14 and puts it into an idle mode.

The UMTS MODEM 13 is in charge of wireless accessing with a base stationof a PMIP network, and the WiMAX MODEM 14 is in charge of wirelessaccessing with a base station of a CMIP network.

The MIP operation unit 15 performs a MIP client function to provide IPmobility of the mobile user equipment according to CMIP and is mountedat an IF spec of the mobile user equipment 10.

FIG. 5 is a timing diagram illustrating an initial access procedure foraccessing a UMTS network.

3GPP specification defines an initial access procedure for accessing aUMTS network at mobile user equipment. Additional signaling procedurefor driving Proxy Mobile IP (PMIP) is a Proxy Registration ReQuest(PRRQ) message and a Proxy ReQuest (PRRP) message exchanged between thePMA function of GGSN and the HA.

When the HA receives a PRRQ message from the GGSN, the HA allocates aHome IP address (HoA) for mobile user equipment and transfers a PRRPmessage with a corresponding IP address to the GGSN. The GGSN notifiesthe allocated IP address to the mobile user equipment using a PDPcontext message.

After allocating the IP address to the mobile user equipment, the mobileuser equipment performs registration at a MIH Information Server (MIIS)and downloads handover related policy and network configurationinformation from the MIIS.

Hereinafter, such an initial access procedure for accessing the UMTSnetwork will be described in detail.

At step S501, the UMTS MODEM of the mobile user equipment performs awireless access and authentication procedure for accessing the UMTSnetwork. That is, the UMTS MODEM of the mobile user equipment performsthe wireless access and authentication procedure with a GGSN using a L2Connection Establish and Authentication message at step S501.

At steps S502 to S504, the UMTS MODEM of the mobile user equipmentperforms a path establishment request procedure for the data service ofthe UMTS network. That is, the UMTS MODEM of the mobile user equipmentrequests ‘Packet Data Protocol Context’ activation to a Serving GPRSSupport Node (SGSN) using an ‘Activate Packet Data Protocol (PDP)Context Request’ message at step S502. At step S503, the SGSN requeststhe GGSN to create ‘Packet Data Protocol Context’ using a ‘Create PDPContext Request’ message. At step S504, the GGSN requests accesspermission to an AAA server and receives authentication from the AAAserver.

At steps S505 and S506, the GGSN performs a PMIP registration procedure.That is, the GGSN requests registration to the Home Agent using a ProxyRegistration ReQuest (PRRQ) message. At step S506, the Home Agentsecures and allocates an home IP address for the mobile user equipmentand transfers the corresponding IP address to the GGSN by loading thecorresponding IP address in the Proxy Registration RePly (PRRP) message.Particularly, the PMIP client device mounted at the GGSN performs thePMIP registration procedure to the Home Agent.

At step S507, the GGSN transfers an IP address to be allocated to themobile user equipment to the SGSN using a ‘Create PDP Context Request’message. At step S508, the SGSN allocates the IP address to the mobileuser equipment using an ‘Activate PDP Context Accept’ message.

After allocating the IP address to the mobile user equipment, the mobileuser equipment transmits to a MIIS a MIH_Register-REQ message. Then, theMIIS performs a registration procedure for corresponding mobile userequipment and transmits a MIH_Register-RSP message to the mobile userequipment at step S509. The mobile user equipment downloads informationabout the policy of the heterogeneous protocol handover and networkconfiguration, which are required to make decision for handover.

FIG. 6 is a flowchart illustrating a method for performing handover in aheterogeneous protocol mixed network in accordance with a firstembodiment of the present invention. For example, the flowchart of FIG.6 shows a handover signaling procedure from a UMTS network to a WiMAXnetwork (a cancelation after connection scenario).

Mobile user equipment accesses a UMTS network and transmits and receivestraffic through a GGSN.

If the mobile user equipment senses a WiMAX base station and if anintensity of a signal received from the WiMAX base station issufficiently enough to provide a WiMAX service, a handover process maybe performed from the UMTS network to a WiMAX network.

If it is decided to perform a handover process, the mobile userequipment transmits a Handover Commit message to the GGSN. When themobile user equipment receives a Handover Commit response message fromthe GGSN, the mobile user equipment starts accessing the WiMAX network.

Until the mobile user equipment completely accesses the WiMAX network,the mobile user equipment transmits and receives user traffics throughthe UMT network. After the mobile user equipment completely accesses theWiMAX network, the mobile user equipment transmits a RegistrationReQuest (RRQ) message to the home agent (HA). Here, if a S bit is setupat a RRQ message header, the HA allows both of the UMTS network and theWiMAX network simultaneous binding. After simultaneously binding theUMTS network and the WiMAX network, the HA may transmit user trafficthrough the UMTS network and the WiMAX network at the same time.

The mobile user equipment receives a Registration RePly (RRP) message,the mobile user equipment exchanges a Handover Complete message with theMIIS and severs the UMTS network access.

When the GGSN senses the access cancelation, the GGSN transmits to theHA a PRRQ message having lift time setup with 0. The HA receives thePRRQ message from the GGSN and severs a PMIP tunnel between the HA andthe GGSN.

Hereinafter, a handover processing method in a heterogeneous protocolmixed network in accordance with an embodiment of the present inventionwill be described in more detail.

At steps S601 to S604, the mobile user equipment performs a procedurefor informing the MIIS of handover. If the MIIS has a function detectinga state of a target network to handover, the MIIS may advice the mobileuser equipment through a response message transmitted to the mobile userequipment. For example, the MIIS may determine whether the targetnetwork to handover has sufficient wireless resources or not and mayadvise the mobile user equipment whether it is proper to perform thehandover process or not based on the determination result.

That is, when the handover from the UMTS network to the WiMAX networkstarts at the step S601, the mobile user equipment transmits aMIH_MN_HO_Commit-REQ message to the GGSN at step S602. At step S603, theGGSN transmits to the MIIS a MIH_N2N_HO Commit-REQ message and receivesa MIH_N2N_HO Commit-RSP message as a response thereof at step S603. Atstep S604, the GGSN transmits the MIH_MN_HO_Commit-RSP message to themobile user equipment.

Then, the mobile user equipment performs a wireless access andauthentication procedure for accessing the WiMAX network at steps S605to S610.

At step S605, the mobile user equipment controls timing of a wirelesssignal according to a distance between a base station and a mobile userequipment and selects a frequency channel to be used using a procedureof transferring a RNG-REQ message to a base station of the WiMAX networkand receiving a RNG-RSP message as a response thereof from the basestation of the WiMAX network.

At step S606, the mobile user equipment negotiates a providing functionwith the base station using a procedure of transferring a SS BasicCapability request (SBC-REQ) message to the base station of WiMAXnetwork and receiving a SBC response (SBC-RSP) message from the basestation of WiMAX network as a response thereof.

At step S607, the mobile user equipment requests authentication using aPrimary Key Management (PKM) request (PKM-REQ) message between themobile user equipment and the base station of WiMAX network. Then, anauthentication procedure is performed through an EPA request (EPA-REQ)message between the base station of WiMAX network and an ASN-GW of theWiMAX network and an Access Request/Accept message between the ASN-GW ofthe WiMAX network and the AAA server. Then, the authentication result istransferred through a PKM response (PKM-RSP) message between the mobileuser equipment and the base station of the WiMAX network.

At step S608, negotiation with a network for Internet service isrequested using a Registration Request (REG-REQ) message between themobile user equipment and the base station of WiMAX network. Thenegotiation procedure is performed for the Internet service through aRegistration Request (REG-REQ) message and a Registration Response(REG-RSP) message between the base station of WiMAX network and theASN-GW of WiMAX network. The negotiation result is transferred using aREG response (REG-RSP) message between the mobile user equipment and thebase station of WiMAX network.

The mobile user equipment performs a service flow generation procedurefor Internet service using a Dynamic Service Addition REQuest (DSA-REQ)message, a DSA response (DSA-RSP) message, and a DSA acknowledgement(DSA-ASK) between the base station of WiMAX network and the mobile userequipment at step S609.

At step S610, the mobile user equipment performs a CCoA allocationprocedure to allocate an IP address through a Dynamic Host ConfigurationProtocol (DHCP). That is, the mobile user equipment requests IPallocation by transferring a DHCP Discover message to an ASN-GW of WiMAXnetwork through the base station of WiMAX network. The ASN-GW receivesthe DHCP Discover message and receives an IP address to be allocated tothe mobile user equipment from the home agent. Then, the ASN-GW of WiMAXnetwork informs that the corresponding IP address is available bytransferring the IP address transferred from the home agent to themobile user equipment through a DHCP Offer message. The mobile userequipment informs an intention of using the IP address by transferring aDHCP Request message to the ASN-GW of WIMAX network. Then, the ASN-GW ofWIMAX network finally allows the mobile user equipment to use thecorresponding IP address by transferring a DHCP ACK message to themobile user equipment.

After finishing the WiMAX network access procedure, the mobile userequipment performing CMIP registration to the HA by transferring aRegistration ReQuest (RRQ) message to the HA at step S611. The HA allowssimultaneous binding to both of the UMTS network and the WiMAX networkif a S bit of the RRQ message header is setup as 1. After establishingthe simultaneous binding, the HA can transmit user traffic to both ofthe UMTS network and the WiMAX network at the same time. That is, a CMIPtunnel is established to the mobile user equipment while maintaining anexisting PMIP tunnel according to the simultaneous binding. Accordingly,user traffic can be transmitted to the UMTS network and the WiMAXnetwork at the same time. Here, the CMIP client included in the mobileuser equipment substantially performs a CMIP registration procedure withthe Home Agent.

After the mobile user equipment receives the RRP message from the HA atstep S612, the mobile user equipment performs a procedure of informingthe MIIS of handover completion at steps S613 to S615. The MIIS noticesthe handover completion to the GGSN of the UMTS network which is aprevious access network.

When the mobile user equipment transmits a MIH_MN_HO complete request(MIH_MN_HO_Complete-REQ) message to the MIIS at step S613, the MIIStransmits the MIH_N2N_HO Complete-REQ message and receives a MIH_N2N_HOcomplete response (MIH_N2N_HO_Complete-RSP) message as a responsethereof at step S614. Then, a MIH_MN_HO_Complete-RSP message istransmitted to the mobile user equipment at step S615.

When the mobile user equipment requests canceling a UMTS link to theGGSN at step S616, the GGSN performs a PMIP registration cancelingprocedure at steps S617 and S618. That is, the GGSN requests cancellingregistration by setting up a life time of a Proxy Registration ReQuest(PRRQ) message to ‘0’ at step S617. At step S618, the home agenttransmits a Proxy Registration RePly (PRRP) message to the GGSN to severa PMIP tunnel between the Home Agent and the GGSN. Particularly, a PMIPclient included in the GGSN performs the PMIP registration cancelationprocedure with the home agent.

When the PMIP tunnel between the home agent and the GGSN is canceled asdescribed above, only the CMIP tunnel between the Home Agent and themobile user equipment is maintained. Accordingly, user traffic iscontinuously transmitted or received through the corresponding CMIPtunnel.

Hereinafter, a handover procedure in a heterogeneous protocol mixednetwork after the initial access procedure for accessing the UMTSnetwork will be described.

The MIP sensor 11 of the mobile user equipment 10 monitors a network toaccess when power is turned on, when a user request Internet service, orwhen a user gives instruction of accessing a predetermined network. Inthe network monitoring procedure, it is assumed that the IMP sensor 11senses accessing the PMIP network.

The access controller 12 activates the UMTS MODEM 13. Accordingly, theUMTS MODEM 13 performs an accessing try procedure for resourcenegotiation between a base station and a GGSN 30 for accessing the UMTSnetwork and for exchanging information between the mobile user equipment10 and a base station.

Then, the GGSN 30 performs authentication of the mobile user equipment10 through an AAA server located at the UMTS network. The AAA server ofthe PMIP network shares authentication of the mobile user equipment 10with an AAA server of the CMIP network for interworking with the CMIPnetwork.

Then, the mobile user equipment accesses the GGSN 30 by the UMTS MODEM13, and the GGSN 30 receives a HoA from the HA 40. The GGSN 30 providesthe received HoA to the mobile user equipment 10 and requests bindingupdate (location registration) of the mobile user equipment 10 to the HA40 using own address as a CCoA address. When requesting the bindingupdate, a network identifier is transmitted to inform accessing the PMIPnetwork. The HA 40 detects that an access network currently accessed bythe mobile user equipment 10 is the PMIP network based on the networkidentifier.

The HA 40 performs binding update, transmits the binding update resultto the GGSN 30, and generates a PMIP tunnel between the HA 40 and theGGSN 30.

The mobile user equipment 10 transmits and receives data to/from thecorrespondent node 50 through the PMIP tunnel.

When a user instructs accessing a CMIP network or when the mobile userequipment 10 enters the CMIP network from the PMIP network while themobile user equipment 10 is transmitting and receiving data to/from thecorrespondent node 50, the MIP sensor 11 of the mobile user equipment 10generates a handover event. Then, the access controller 12 interruptsthe operation of the UMTS MODEM 13 and activates the WiMAX MODEM 14 toinstruct accessing the CHIP network.

The WiMAX MODEM 14 accesses the ASN-GS 20 through resource negotiationwith a base station of the CMIP network and exchanging information. TheMIP driver 15 is allocated with an IP address such as CCoA through aDHCP procedure using a FA function of the ASN-GW. The mobile userequipment 10 continuously uses the HoA previously allocated from thePMIP network as a home address.

The MIP driver 15 requests binding update such as location registrationto the HA 40 using the CCoA. When requesting the binding update, anetwork identifier is transmitted together to inform accessing the CMIPnetwork. The HA 40 detects a network currently accessed by the mobileuser equipment 10 is a CMIP network.

The HA 40 performs binding update, transmits the binding update resultto the mobile user equipment 10, and creates a CMIP tunnel to the mobileuser equipment 10.

The mobile user equipment 10 transmits and receives data to/from thecorrespondent node 50 through the CMIP tunnel. Here, the datatransmission and reception between the mobile user equipment 10 and thecorrespondent node 50 is performed through the PMIP tunnel before theCMIP tunnel is created.

FIG. 7 is a flowchart illustrating an initial access procedure foraccessing a WiMAX network.

The initial access procedure for accessing a WiMAX network at mobileuser equipment is defined in IEEE 802.16e specification.

An additional signaling procedure for driving CMIP is a RegistrationReQuest (RRQ) message and a Registration RePly (RRP) message exchangedbetween mobile user equipment and a Home Agent.

The ASN-GW secures an IP address to be used as a Care-of-Address (CoA)for the mobile user equipment and allocates the secured IP address tothe mobile user equipment. Then, the mobile user equipment transmits theRRQ message to the HA. The HA receives the RRQ message, secures a HomeIP Address (HoA), and informs the mobile user equipment of thecorresponding HoA by transmitting a Registration RePly (RRP) message tothe mobile user equipment.

After the HoA is allocated to the mobile user equipment, the mobile userequipment performs registration at a MIH Information Server (MIIS) anddownloads from the MIIS heterogeneous handover related policy andnetwork configuration information, which are required to decidehandover.

Hereinafter, the initial access procedure for accessing a WiMAX networkwill be described in detail.

At steps S701 to S706, the mobile user equipment performs a wirelessaccess and authentication procedure for accessing a WiMAX network.

At step S701, the mobile user equipment transfers a RNG request(RNG-REQ) message to a base station of WiMAX network and receives a RNGresponse (RNG-RSP) message as a response thereof from the base stationof WiMAX network, thereby controlling timing of a wireless signalaccording to a distance between the base station and the mobile userequipment and selecting a useable frequency channel.

At step S702, the mobile user equipment negotiates with the base stationto provide related functions using a procedure of transferring a SSBasic Capability request (SBC-REQ) message to the base station of WiMAXnetwork and receiving a SBC response (SBC-RSP) message from the basestation of WiMAX network.

At step S703, when authentication is requested using a Primary KeyManagement request (PKM-REQ) message between the mobile user equipmentand the base station of WiMAX network, an authentication procedure isperformed using an EPA request (EPA-REQ) message and an EPA response(EPA-RSP) message between the base station of WiMAX network and theASN-GW of WIMAX network, and an access request/accept message betweenthe ASN-GW of WIMAX network and an AAA server. The authentication resultis transferred through a PKM response (PKM-RSP) message between themobile user equipment and the base station of WiMAX network.

At step S704, when requesting negotiation for Internet service using aregistration request (REG-REQ) message between the mobile user equipmentand the base station of WiMAX network, the negotiation procedure forInternet service is performed using a REG-REQ message and a REG-RSPmessage between the base station of WiMAX network and the ASN-GW ofWIMAX network. Then, the negotiation result is transferred through aREG-RSP message between the mobile user equipment and the base stationof WiMAX network.

At step S705, the mobile user equipment performs a service flowgeneration procedure for Internet service using a Dynamic ServiceAddition REQuest (DSA-REQ) message, a DSA RESponse (DSA-RSP) message,and a DSA Acknowledgment (DSA-ACK) message between the base station ofWiMAX network and the mobile user equipment.

At step S706, the mobile user equipment performs a CCoA allocationprocedure for allocation an IP address through a Dynamic HostConfiguration Protocol (DHCP). That is, the mobile user equipmentrequests IP allocation by transferring a DHCP Discover message to theASN-GW of WIMAX network through the base station of WiMAX network. TheASN-GW of WIMAX network receiving the DHCP Discover message is providedwith the IP address allocated to the mobile user equipment from the HomeAgent. Then, the ASN-GW of WIMAX network transfers the provided IPaddress from the home agent to the mobile user equipment through a DHCPOffer message, thereby informing that the corresponding IP address is ausable IP address. After that, the mobile user equipment transfers aDHCP Request message to the ASN-GW of WIMAX network, thereby notifyingan intention of using the corresponding IP address. Then, the ASN-GW ofWIMAX network finally allows the mobile user equipment to use thecorresponding IP address by transferring a DHCP ACK message to themobile user equipment.

After completely accessing the WiMAX network as described above, themobile user equipment transfers a Registration REQuest (RRQ) message atstep S707 and receives a Registration RePly (RRP) message from the HA atstep S708 to perform a CMIP registration procedure. Particularly, a CMIPclient included in the mobile user equipment performs the CMIPregistration procedure with the home agent.

When the mobile user equipment transmits a MIH registration REQuest(MIH_Register-REQ) message to the MIIS, the MIIS performs theregistration procedure for the corresponding mobile user equipment andtransmits a MIH registration response (MIH_Register-RSP) message to themobile user equipment at step S709. The mobile user equipment downloadsinformation on heterogeneous handover related policy and networkconfiguration from the MIIS.

FIG. 8 is a flowchart illustrating a method for processing handover in aheterogeneous protocol mixed network in accordance with an embodiment ofthe present invention. For example, the flowchart of FIG. 8 is ahandover signaling procedure from a WiMAX network to a UMTS network.

After the mobile user equipment accesses the WiMAX network, the mobileuser equipment transmits and receives user traffic through the WiMAXnetwork.

If the intensity of a signal received from a base station of the WiMAXnetwork becomes weak, handover may be performed from the WiMAX networkto the UMTS network.

After deciding to perform the handover process, the mobile userequipment transmits a Handover Commit message to the MIIS. The MIIStransmits the Handover Commit message to a target GGSN of the UMTSnetwork. The GGSN receives the Handover Commit message and performs aPMIP registration procedure. If a S bit of a PRRQ message header issetup as “1”, the HA allows simultaneous biding.

When the mobile user equipment receives a Handover Commit responsemessage, the mobile user equipment starts accessing the UMTS network.Before the mobile user equipment completely accesses the UMTS network,the mobile user equipment uses the WiMAX network to transmit and receiveuser traffic.

After the mobile user equipment completely accesses the UMTS network,the mobile user equipment exchanges a Handover Complete message with theGGSN and transmits a RRQ message to the HA by setting up a lift time ofthe RRQ message as “0”. The HA receives the RRQ message and severs aCMIP tunnel between the mobile user equipment and the HA.

Hereinafter, a handover processing method in a heterogeneous protocolmixed network in accordance with a second embodiment of the presentinvention will be described.

At steps S801 to S804, the mobile user equipment performs a procedurefor informing the MIIS that the mobile user equipment will perform ahandover process. The MIIS informs the GGSN that the mobile userequipment will perform a handover process, thereby invoking the GGSN toperform a PMIP registration procedure at steps S805 and S806.

At step S801, a handover process from a WiMAX network to a UMTS networkbegins. At step S802, the mobile user equipment transmits a MIH_MN_HOcommit request (MIH_MN_HO Commit-REQ) message to the MIIS. At step S802,the MIIS transmits a MIH_N2N_HO commit request (MIH_N2N_HO Commit-REQ)message to the GGSN and receives a MIH_N2N_HO commit response(MIH_N2N_HO_Commit-RSP) message as a response thereof. At step S804, theMIIS transmits a MIH_MN_HO commit response (MIH_MN_HO_Commit-RSP)message to the mobile user equipment.

The GGSN transmits a Registration ReQuest (RRQ) message to the HA atstep S805 and receives a Registration RePly (RRP) message as a responsethereof from the HA at step S806, thereby performing a PMIP registrationprocedure. Here, if a S bit of a RRQ message header is setup as “1”, theHA allows simultaneous binding to the WiMAX network and the UMTSnetwork. After establishing simultaneous binding, the HA can transmituser traffic to the WiMAX network and the UMTS network at the same time.That is, a PMIP tunnel is established to the GGSN while maintaining anexisting CMIP tunnel according to the simultaneous binding. Accordingly,user traffic can be transmitted to the WiMAX network and the UMTSnetwork at the same time.

At step S807, the mobile user equipment performs a wireless access andauthentication procedure for accessing a UMTS network. That is, themobile user equipment uses a L2 Connection Establish and Authenticationmessage to perform a wireless access and authentication procedure withthe GGSN at the step S807.

At steps S808 to S810, the mobile user equipment performs a pathestablishing request procedure for UMTS network data service. That is,the mobile user equipment requests the SGSN to activate ‘Packet dataProtocol Context’ using an ‘Activate PDP Context Request’ message atstep S808. At step S809, the SGSN requests the GGSN to create ‘PacketData Protocol Context’ using a ‘Create PDP Context Request’ message. Atstep S810, the GGSN requests the AAA server to authenticatecorresponding accessing and receives the authentication result from theAAA server.

At step S811, the GGSN transfers an IP address to be allocated to themobile user equipment to the SGSN using a Create PDP Context Reqmessage. At step S812, the SGSN allocates the IP address to the mobileuser equipment using an Activate PDP Context Accept message.

At steps S813 to S815, the mobile user equipment performs a procedurefor informing the MIIS of handover completion as follows.

At step S813, the mobile user equipment transmits a MIH_MN_HO completerequest (MIH_MN_HO_Complete-REQ) message to the GGSN. At step S814, theGGSN transmits the MIH_N2N_HO complete request (MIH_N2N_HO_Complete-REQ)message to the MIIS and receives a MIH_N2N_HO complete response(MIH_N2N_HO_Complete-RSP) message as a response thereof. At step S815,the GGSN transmits a MIH_MN_HO complete response(MIH_MN_HO_Complete-RSP) message to the mobile user equipment.

At step S816, the mobile user equipment requests the home agent to severregistration by setting up a lift time of the Registration ReQuest (RRQ)message as ‘0’. At step S817, the Home Agent transmits a RegistrationRePly (RRP) message to the mobile user equipment, thereby canceling aCMIP tunnel between the Home Agent and the mobile user equipment. Then,the mobile user equipment requests the base station of WiMAX network tocancel a WiMAX link at step S818.

After disconnecting the CMIP tunnel between the Home Agent and themobile user equipment, only the PMIP tunnel between the Home Agent andthe GGSN is continuously maintained. Accordingly, user traffic istransmitted or received through the corresponding PMIP tunnel.

FIG. 9 is a flowchart illustrating a method for processing handover in aheterogeneous protocol mixed network in accordance with a thirdembodiment of the present invention.

The handover processing method according to the third embodiment of thepresent invention is performed when mobile user equipment 10 enters aPMIP network again before the mobile user equipment 10 completelyperforms a handover process from a PMIP network to a CMIP network. Sucha case may happen when the mobile user equipment 10 moves at a fastspeed through a locally formed CMIP network or when a user instructsaccessing the PMIP network.

At step S901, a MIP sensor 11 of the mobile user equipment 10 senses anetwork to access when power is turned on, when a user request anInternet service, or when a user instructs accessing a predeterminednetwork. It is assumed that the MIP sensor 11 senses the PMIP network toaccess during such a network sensing procedure.

The access controller 12 activates the UMTS MODEM 13 at step S902.Accordingly, the UMTS MODEM 13 performs a resource negotiation procedurebetween a base station and a GGSN 30 for accessing the PMIP network andan access trying procedure for exchanging information between the mobileuser equipment 10 and the base station at step S903.

Then, the GGSN 30 performs authentication of the mobile user equipment10 through a second AAA server located at the PMIP network. The secondAAA server of the PMIP network shares the authentication of the mobileuser equipment 10 with a first AAA server of the CMIP network forinterworking with the CMIP network.

At step S904, the UMTS MODEM 13 establishes connection to the GGSN 30,and the GGSN 30 is provided with a HoA from the HA 40, provides the HoAto the mobile user equipment 10, and requests the HA 40 binding updatefor the mobile user equipment 10 using own address as a temporal address(CCoA). When requesting the binding update, a network identifierinforming accessing the PMIP network is transmitted together. The HA 40detects that a network currently accessed by the mobile use equipment isthe PMIP network based on the network identifier.

At step S905, the HA 40 performs binding update, transmits the bindingupdate result to the GGSN 30, and creates a PMIP tunnel between the HA40 and the GGSN 30.

At step S906, the mobile user equipment 10 uses the PMIP tunnel toexchange data with a correspondent node 50.

At step S907, the MIP sensor 11 of the mobile user equipment 10 createsa handover event while the mobile user equipment 10 is transmitting andreceiving data to/from the correspondent node 50 if a user instructsaccessing the CMIP network or if the mobile user equipment 10 gets outof the PMIP network and enters the CMIP network.

At step S908, the access controller 12 interrupts the operation of theUMTS MODEM 13 and activates the WiMAX MODEM 14 to access the WiMAXnetwork. Accordingly, the WiMAX MODEM 14 accesses the ASN-GW 20 throughresource negotiation and information exchange with the base station ofthe CMIP network. At step S909, the MIP driver 15 receives an IP address(CCoA) using a FA function of the ASN-GW or through a Dynamic HostConfiguration Protocol (DHCA) procedure. The mobile user equipment 10uses a HoA previously allocated from the PMIP network as a home address.

At step S910, the MIP driver 15 transmits a binding update (BU) messagefor requesting binding update to the HA 40 using CCoA.

If the HIP sensor 11 senses the handover process to the PMIP networkbefore the mobile user equipment 10 receives a RRP message as a responsemessage of a BU message after transmitting the BU message at step S911,the access controller 12 determine cancelation of the handover processto the CMIP network at step S912. At step S913, the access controller 12interrupts the operation of the WiMAX MODEM 14 and activates the UMTSMODEM 13.

The mobile user equipment 10 uses the previous PMIP tunnel createdbefore the CMIP tunnel is created according to the generation of thehandover event from the PMIP network to the CMIP network. Since thehandover cancelation procedure (S912) is performed prior to thegeneration of the CMIP tunnel, the PMIP tunnel can be maintained as itis. Therefore, the mobile user equipment 10 can continuously transmitand receive data to/from the correspondent node 50 through the PMIPnetwork only by activating the UMTS MODEM 413.

FIG. 10 is a flowchart illustrating a method for processing handover ina heterogeneous protocol mixed network in accordance with a fourthembodiment of the present invention. Here, the heterogeneous protocolmixed network is a network including a CMIP network and a PMIP network.

At step S1001, a MIP sensor 11 of mobile user equipment 10 senses anetwork to access when power is turned or, when a user request anInternet service, or when a user instructs accessing a predeterminednetwork. In the step S1001, it is assumed that the MIP sensor 11 sensesthe CMIP network to access.

The access controller 12 activates the WiMAX MODEM 14 at step S1002.

Accordingly, the WiMAX MODEM 14 performs an access try procedure fornegotiating a base station for resources to access the CMIP network atstep S1003.

At step S1004, the ASN-GW 20 authenticates the mobile user equipment 10through a first AAA server located at the CMIP network. At step S1005,the first AAA server shares the authentication result with a second AAAserver located at the PMIP network for interworking with the PMIPnetwork.

After authentication, the WiMAX MODEM 14 establishes connection to theASN-GW 20. When the ASN-GW 20 includes a FA function, the ASN-GW 20creates a CCoA and allocates the CCoA to the mobile user equipment 10.When the ASN-GW 20 does not include the FA function, the mobile userequipment 10 is allocated with a dynamic IP address through a DHCPprocedure and uses the allocated IP address as a CCoA at step S1006. Inthis case, the mobile user equipment 10 uses a fixed IP as a HoA if themobile user equipment 10 is allocated with a HoA from the HA 40 or is inan IPv6 environment.

At step S1007, the mobile user equipment 10 requests registration to theHA 40 by the MIP driver 15 using a BU message and is allocated a Home IPaddress. The BU message includes a network identifier informingaccessing the CMIP network. The HA 40 uses the network identifier todetect that a network currently accessed by the mobile user equipment 10is the CMIP network at step S1008.

At step S1009, a CMIP tunnel is created between the mobile userequipment 10 and the HA 40.

At step S1010, data is transmitted and received between the mobile userequipment 10 and the correspondent node 50 through the created CMIPtunnel.

As described above, the mobile user equipment 10 perform a procedure foraccessing a PMIP network and creating a PMIP tunnel in order to preparea handover to a PMIP network in advance while the mobile user equipment10 is transmitting and receiving data by accessing the CMIP network atsteps S1003 to S1010.

At step S1011, the access controller 12 of the mobile user equipment 10activates the UMTS MODEM 13 and accesses the GGSN 30 of the PMIPnetwork. Here, the mobile user equipment 10 informs the GGSN 30 oftemporal access.

At step S1012, the access controller 12 of the mobile user equipment 10changes the state of the UMTS MODEM 13 to an idle state so the UMTSMODEM 13 is in an un-used state although it is activated.

The GGSN 30 requests the HA 40 to perform binding update for the mobileuser equipment 10 using own address as a CCoA according to the temporalaccess of the mobile user equipment 10 and transmits a temporal accessidentifier to inform the temporal access at step S1013. Alternately, themobile user equipment 10 may provide a temporal access informing messageto the HA 40 through the CMIP network in order to inform the HA 40 ofthe temporal access.

Meanwhile, since the mobile user equipment 10 already has a HoA, theGGSN 30 can omit performing a process of receiving the HoA from the HA40.

At step S1014, the HA 40 determines based on the temporal accessidentifier that the mobile user equipment 10 tries to access the PMIPnetwork in advance, not try to handover to the PMIP network.

Accordingly, the HA 40 performs binding update for the location of themobile user equipment 10 with a CCoA transferred when requesting bindingupdate and creates a PMIP tunnel to the GGSN 30 at step S1015. Then, thecreated PMIP tunnel is managed as an idle state at step S1016. Here, theidle state means a state that maintains the created PMIP tunnel withoutusing.

Accordingly, the mobile user equipment 10 can immediately handover tothe PMIP network by managing the PMIP tunnel in the idle state after theHA 40 generates the PMIP tunnel when the HA 40 generates the CMIP tunnelwhile the mobile user equipment 10 is transmitting and receiving datawith a correspondent node 50 through the CMIP network.

Accordingly, when a handover event from the CMIP network to the PMIPnetwork is generated at step S1017, the mobile user equipment 10 canomit a procedure of accessing the PMIP network by changing the UMTSMODEM 13 from the IDLE mode to the activation mode at step S1018.

When the MIP driver 15 of the mobile user equipment 10 transmits the IMPregistration cancel message to the HA 40 to sever the existing CHIPtunnel, the HA 40 activates the PMIP tunnel, which is in an idle state,and severs the CMIP tunnel at step S1019.

Accordingly, the mobile user equipment 10 can transmit and receive datawith the correspondent node 50 through the PMIP tunnel after thehandover process is completed at step S1020.

In an embodiment of the present invention shown in FIG. 10, the mobileuser equipment 10 accesses the PMIP network in advance to prepare thehandover process while receiving a data service by accessing the CHIPnetwork. However, the mobile user equipment 10 may access the CMIPnetwork to prepare the handover process while receiving a data serviceby accessing the PMIP network.

The above-described methods can also be embodied as computer programs.Codes and code segments constituting the programs may be easilyconstrued by computer programmers skilled in the art to which theinvention pertains. Furthermore, the created programs may be stored incomputer-readable recording media or data storage media and may be readout and executed by the computers. Examples of the computer-readablerecording media include any computer-readable recoding media, e.g.,intangible media such as carrier waves, as well as tangible media suchas CD or DVD.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

MODE FOR INVENTION Industrial Applicability

The present invention may be used in a wireless communication networkincluding heterogeneous protocols such as a Client Mobile IP (CMIP) anda Proxy Mobile IP (PMIP).

SEQUENCE LIST TEXT

1. A method for processing handover at a home agent in a heterogeneous protocol mixed network, comprising: creating a Proxy Mobile Internet Protocol (PMIP) tunnel to an access gateway of a PMIP network when user equipment accesses a PMIP network; creating a Client Mobile Internet Protocol (CMIP) tunnel to the user equipment when the user equipment decides to handover to the CMIP network; and severing the PMIP tunnel when the user equipment completes performing the handover.
 2. The method of claim 1, wherein said creating the CMIP tunnel includes: allowing simultaneous binding to the PMIP network and the CMIP network by receiving a Registration ReQuest (RRQ) message from the user equipment when the user equipment accesses the CMIP network; and transferring a Registration RePly (RRP) message to the user equipment.
 3. The method of claim 1, wherein said creating the PMIP tunnel includes: receiving a Proxy Registration ReQuest (PRRQ) message from the access gateway of the PMIP network when the user equipment accesses the PMIP network; and allocating a home IP address for the user equipment and transferring a Proxy Registration RePly (PRRP) message including the home IP address to the access gateway of the PMIP network.
 4. The method of claim 1, wherein said severing the PMIP tunnel includes: receiving a PRRQ message with a light time setup as “0” from the access gateway of the PMIP network when the user equipment completes performing handover; and severing the PMIP tunnel.
 5. A method for processing handover at a home agent in a heterogeneous protocol mixed network, comprising: creating a Client Mobile Internet Protocol (CMIP) tunnel between user equipment and the home agent when the user equipment accesses a CMIP network; creating a Proxy Mobile Internet Protocol (PMIP) tunnel between the home agent and an access gateway of a PMIP network when the user equipment decides to perform handover to the PMIP network; and severing the CMIP tunnel when the user equipment completes performing handover.
 6. The method of claim 5, wherein said creating the PMIP tunnel includes: receiving a Proxy Registration ReQuest (PRRQ) message from the access gateway of the PMIP network when the user equipment accesses the PMIP network; allowing simultaneous binding (simultaneous registration) to the CMIP network and the PMIP network; and transferring a Proxy Registration ReQuest (PRRQ) message to the access gateway of the PMIP network.
 7. The method of claim 5, wherein said creating the CMIP tunnel includes: receiving a Registration ReQuest (RRQ) message from the user equipment when the user equipment accesses the CMIP network; and allocating a home IP address for the user equipment and transferring a Registration RePly (RRP) message including the home IP address to the user equipment.
 8. The method of claim 5, wherein said severing the CMIP tunnel includes: receiving a RRQ message having a life time setup as “0” from the user equipment when the user equipment completes performing handover; and severing the CMIP tunnel.
 9. A method for processing handover at user equipment in a heterogeneous mobility protocol mixed network, comprising: being allocated with a home Internet Protocol (IP) address for the user equipment by accessing a Proxy Mobile IP (PMIP) network; and forming a Client Mobile IP (CMIP) tunnel to a home agent by accessing the CMIP network when the user equipment decides to perform handover to the CMIP network; wherein the home agent severs a PMIP tunnel to an access gateway of the PMIP network when the home agent completes performing handover to the user equipment.
 10. The method of claim 9, wherein said forming a CMIP tunnel includes: transmitting a Registration ReQuest (RRQ) message to the home agent; and receiving a Registration RePly (RRP) message from the home agent. wherein the home agent allows simultaneous binding to the CMIP network and the PMIP network according to the RRQ message.
 11. The method of claim 9, wherein in said being allocated with a home IP address, the home IP address allocated by the home agent is transferred to an access gateway of the PMIP network.
 12. A method for processing handover at user equipment in a heterogeneous mobility protocol mixed network, comprising: forming a Client Mobile Internet Protocol (CMIP) tunnel to a home agent by accessing a CMIP network; and accessing a Proxy Mobile Internet Protocol (PMIP) network when the user equipment decides to perform handover to a Proxy, wherein the home agent severs the CMIP tunnel to the user equipment when the user equipment completes performing the handover.
 13. The method of claim 12, wherein said forming a CMIP tunnel includes: transmitting a Registration ReQuest (RRQ) message to the home agent; and receiving a Registration RePly (RRP) message from the home agent. wherein the home agent allocates a home IP address for the user equipment according to the RRQ message. 14-18. (canceled) 